The Great Influenza: The Epic Story of the Deadliest Plague in History

by John M. Barry

The pressure to find an answer did not bother him; much of his polio research had been conducted in the midst of an epidemic so extreme that New York City had required people to obtain passes to travel.

Lewis was correct. In 1918 an influenza virus emerged—probably in the United States—that would spread around the world, and one of its earliest appearances in lethal form came in Philadelphia. Before that worldwide pandemic faded away in 1920, it would kill more people than any other outbreak of disease in human history.

The lowest estimate of the pandemic’s worldwide death toll is twenty-one million, in a world with a population less than one-third today’s. That estimate comes from a contemporary study of the disease and newspapers have often cited it since, but it is almost certainly wrong. Epidemiologists today estimate that influenza likely caused at least fifty million deaths worldwide, and possibly as many as one hundred million.

Although the influenza pandemic stretched over two years, perhaps two-thirds of the deaths occurred in a period of twenty-four weeks, and more than half of those deaths occurred in even less time, from mid-September to early December 1918. Influenza killed more people in a year than the Black Death of the Middle Ages killed in a century; it killed more people in twenty-four weeks than AIDS has killed in twenty-four years.

In 1753 James Lind conducted a pioneering controlled experiment among British sailors and demonstrated that scurvy could be prevented by eating limes—ever since, the British have been called “limeys.”

Leo Szilard, a prominent physicist, made this point when he complained that after switching from physics to biology he never had a peaceful bath again. As a physicist he would soak in the warmth of a bathtub and contemplate a problem, turn it in his mind, reason his way through it. But once he became a biologist, he constantly had to climb out of the bathtub to look up a fact.

Echoing Hunter’s advice to Jenner, Bernard, a physiologist, told one American student, “Why think? Exhaustively experiment, then think.”)

Influenza is a viral disease. When it kills, it usually does so in one of two ways: either quickly and directly with a violent viral pneumonia so damaging that it has been compared to burning the lungs; or more slowly and indirectly by stripping the body of defenses, allowing bacteria to invade the lungs and cause a more common and slower-killing bacterial pneumonia.

staphylococci live in layers of the skin, which meant that a surgeon had to disinfect not only the skin surface during an operation but layers beneath it.

Einstein reportedly once said that his own major scientific talent was his ability to look at an enormous number of experiments and journal articles, select the very few that were both correct and important, ignore the rest, and build a theory on the right ones.

He had an edgy insecurity and said, “I have never been educated in any branch of learning. There are great gaps in my knowledge.” To fill the gaps, he read. “He read,” his brother Abraham said, “as he ate.” He devoured books, read everything, read omnivorously, from English literature to Huxley and Darwin. He felt he had to learn. His insecurities never fully left him. He talked of “sleepless nights and days of acute fear . . . a maddening nervousness which prevented me from having a quiet moment.”

Emerson said that an institution is the lengthened shadow of one man,

Epidemiological evidence suggests that a new influenza virus originated in Haskell County, Kansas, early in 1918. Evidence further suggests that this virus traveled east across the state to a huge army base, and from there to Europe. Later it began its sweep through North America, through Europe, through South America, through Asia and Africa, through isolated islands in the Pacific, through all the wide world.

His patients said they’d rather have him drunk than someone else sober.

There are three different types of influenza viruses: A, B, and C. Type C rarely causes disease in humans. Type B does cause disease, but not epidemics. Only influenza A viruses cause epidemics or pandemics, an epidemic being a local or national outbreak, a pandemic a worldwide one.

Influenza viruses did not originate in humans. Their natural home is in wild aquatic birds, and many more variants of influenza viruses exist in birds than in humans. But the disease is considerably different in birds and humans. In birds, the virus infects the gastrointestinal tract. Bird droppings contain large amounts of virus, and infectious virus can contaminate cold lakes and other water supplies. Massive exposure to an avian virus can infect man directly, but an avian virus cannot go from person to person. It cannot, that is, unless it first changes, unless it first adapts to humans.

By entering the cell, as opposed to fusing with the cell on the cell membrane—which many other viruses do—the influenza virus hides from the immune system. The body’s defenses cannot find it and kill it.

Hemagglutinin occurs in eighteen known basic shapes, neuraminidase in nine, and they occur in different combinations with subtypes. Virologists use these antigens to identify what particular virus they are discussing or investigating. “H1N1,” for example, is the name given the 1918 virus, currently found in swine.

Some virologists theorize that pigs provide a perfect “mixing bowl,” because the sialic-acid receptors on their cells can bind to both bird and human viruses. Whenever an avian virus infects swine at the same time that a human virus does, reassortment of the two viruses can occur. And an entirely new virus can emerge that can infect man. In 1918 veterinarians noted outbreaks of influenza in pigs and other mammals, and pigs today still get influenza from a direct descendant of the 1918 virus. But it is not clear whether pigs caught the disease from man or man caught it from pigs.

Influenza pandemics generally infect from 15 to 40 percent of a population;

In recent years public health authorities have at least twice identified a new virus infecting humans but successfully prevented it from adapting to man. To prevent the 1997 Hong Kong virus, which killed six of eighteen people infected, from adapting to people, public health authorities had every single chicken then in Hong Kong, 1.2 million of them, slaughtered.

An even greater slaughter of animals occurred in the spring of 2003 when a new H7N7 virus appeared in poultry farms in the Netherlands, Belgium, and Germany. This virus infected eighty-two people and killed one, and it also infected pigs. So public health authorities killed nearly thirty million poultry and some swine.

The Fuel Administration controlled fuel distribution (and to save fuel it also instituted daylight savings time).

these men focused on the biggest killer in war—not combat, but epidemic disease. Throughout the wars in history more soldiers had often died of disease than in battle or of their wounds.

He loved learning and set aside a fixed amount of minutes each day for reading, rotating his attention among fiction, science, and classical literature.

Pneumonia maintained its position as the leading cause of death in the United States until 1936. It and influenza are so closely linked that modern international health statistics, including those compiled by the United States Centers for Disease Control, routinely classify them as a single cause of death.

Influenza causes pneumonia either directly, by a massive viral invasion of the lungs, or indirectly—and more commonly—by destroying certain parts of the body’s defenses and allowing so-called secondary invaders, bacteria, to infest the lungs virtually unopposed.

Horses were injected with gradually increasing doses of virulent bacteria. The bacteria made the toxin. In turn, the horse’s immune system generated antibodies that bound to and neutralized the toxin. The horse was then bled, solids removed from the blood until only the serum remained, and this was then purified into the antitoxin that had become so common and lifesaving. An identical process produced tetanus antitoxin, Flexner’s serum against meningitis, and several other sera or antitoxins. Scientists were vaccinating the horse against a disease, then extracting the horse antibodies and injecting them into people. This borrowing of immune-system defenses from an outside source is called “passive immunity.” When vaccines are used to stimulate people’s own immune systems directly, so that they develop their own defenses against bacteria or viruses, it is called “active immunity.”

Spain actually had few cases before May, but the country was neutral during the war. That meant the government did not censor the press, and unlike French, German, and British newspapers—which printed nothing negative, nothing that might hurt morale—Spanish papers were filled with reports of the disease, especially when King Alphonse XIII fell seriously ill. The disease soon became known as “Spanish influenza” or “Spanish flu,” very likely because only Spanish newspapers were publishing accounts of the spread of the disease that were picked up in other countries.

THE 1918 INFLUENZA PANDEMIC, like many other influenza pandemics, came in waves. The first spring wave killed few, but the second wave would be lethal.

Around the world from Boston, in Bombay, which like so many other cities had endured a mild epidemic in June, the lethal virus exploded almost simultaneously. There it quickly began killing at a rate more than double that of a serious epidemic of bubonic plague in 1900.

Total war requires sacrifice and good morale makes sacrifices acceptable, and therefore possible. The sacrifices included inconveniences in daily life. To contribute to the war effort, citizens across the country endured the “meatless days” during the week, the one “wheatless meal” every day. All these sacrifices were of course voluntary, completely voluntary—although Hoover’s Food Administration could effectively close businesses that did not “voluntarily” cooperate. And if someone chose to go for a drive in the country on a “gasless Sunday,” when people were “voluntarily” refraining from driving, that someone was pulled over by hostile police.

He reported finding the masks so successful that after less than three weeks of experimenting he had abandoned testing and simply started using them as “a routine measure.” He also made the more general point that “one of the most vital measures in checking contagion” is eliminating crowding. “Increasing the space between beds in barracks, placing the head of one soldier opposite the feet of his neighbor, stretching tent flags between beds, and suspending a curtain down the center of the mess table, are all of proved value.”

During the course of the epidemic, 47 percent of all deaths in the United States, nearly half of all those who died from all causes combined—from cancer, from heart disease, from stroke, from tuberculosis, from accidents, from suicide, from murder, and from all other causes—resulted from influenza and its complications. And it killed enough to depress the average life expectancy in the United States by more than ten years. Some of those who died from influenza and pneumonia would have died if no epidemic had occurred. Pneumonia was after all the leading cause of death. So the key figure is actually the “excess death” toll. Investigators today believe that in the United States the 1918–19 epidemic caused an excess death toll of about 675,000 people. The nation then had a population between 105 and 110 million, while it was approaching 300 million in 2006. So a comparable figure today would be approximately 1,750,000 deaths.

the single greatest number of deaths occurred in men and women aged twenty-five to twenty-nine, the second greatest number in those aged thirty to thirty-four, the third greatest in those aged twenty to twenty-four. And more people died in each of those five-year groups than the total deaths among all those over age sixty.

The immune system changes with age. Young adults have the strongest immune system in the population, most capable of mounting a massive immune response. Normally that makes them the healthiest element of the population. Under certain conditions, however, that very strength becomes a weakness. In 1918 the immune systems of young adults mounted massive responses to the virus. That immune response filled the lungs with fluid and debris, making it impossible for the exchange of oxygen to take place. The immune response killed.

The influenza outbreak in 1997 in Hong Kong, when a new virus jumped from chickens to humans, killed only six people and it did not adapt to man. More than a million chickens were slaughtered to prevent that from happening, and the outbreak has been much studied.

(In 2003 a new coronavirus that causes SARS, “severe acute respiratory syndrome,” appeared in China and quickly spread around the world. Coronaviruses cause an estimated 15 to 30 percent of all colds and, like the influenza virus, infect epithelial cells. When the coronavirus that causes SARS does kill, it often kills through ARDS, although since the virus replicates much more slowly than influenza, death from ARDS can come several weeks after the first symptoms.)

New York City was panicking, terrified. Copeland tried to reassure the public by announcing a strict quarantine, though no quarantine was actually implemented. There were literally hundreds of thousands of people sick simultaneously, many of them desperately sick. The death toll ultimately reached thirty-three thousand for New York City alone, and that understated the number considerably, since statisticians later arbitrarily stopped counting people as victims of the epidemic even though people were still dying of the disease at epidemic rates—still dying months later at rates higher than anywhere else in the country. It was impossible to get a doctor, and perhaps more impossible to get a nurse. Reports came in that nurses were being held by force in the homes of patients too frightened and desperate to allow them to leave. Nurses were literally being kidnapped. It did not seem possible to put more pressure on the laboratory. Yet more pressure came.

1918 Influenza

many years later a young graduate student entered a laboratory and saw a renowned Harvard professor at the sink washing glassware while his technician was performing a complex task at the workbench. The student asked him why the technician was not washing the glassware. “Because,” the professor replied, “I always do the most important part of the experiment, and in this experiment the most important thing is the cleanliness of the glassware.”

the Gram test. In this test, bacteria are stained with crystal violet, treated with iodine, washed with alcohol, and then stained again with a contrasting dye. Bacteria retaining the violet color are called “Gram-positive.” Those that do not are “Gram-negative.” The result of the Gram test is comparable to a witness identifying an assailant as white or black; the answer simply eliminates some possible suspects.

The best institutions avoid the worst aspects of bureaucracy in two ways. Some are not really institutions at all. They are simply a loose confederation of individuals, each of whom remains largely a free agent whose achievements are independent of the institution but who also shares and benefits from association with others. In these cases the institution simply provides an infrastructure that supports the individual, allowing him or her to flourish so that the whole often exceeds the sum of the parts. (The Rockefeller Institute was such an institution.) Other institutions avoid the worst elements of bureaucracy by concentrating on a clearly defined purpose. Their rules have little to do with such procedural issues as a chain of command; instead rules focus on how to achieve a particular result, in effect offering guidance based on experience. This kind of institution even at its best can still stultify creativity, but such institutions can execute, can do a routine thing efficiently. They resemble professionals trying to do their jobs and duty; they accomplish their tasks.

Surgeon General’s Advice to Avoid Influenza Avoid needless crowding. . . . Smother your coughs and sneezes. . . . Your nose not your mouth was made to breathe thru. . . . Remember the 3 Cs, clean mouth, clean skin, and clean clothes. . . . Food will win the war. . . . [H]elp by choosing and chewing your food well. . . . Wash your hands before eating. . . . Don’t let the waste products of digestion accumulate. . . . Avoid tight clothes, tight shoes, tight gloves—seek to make nature your ally not your prisoner. . . . When the air is pure breathe all of it you can—breathe deeply.

How quaint.

Influenza could not have been contained as SARS was—influenza is far more contagious. But any interruption in influenza’s spread could have had significant impact. For the virus was growing weaker over time. Simply delaying its arrival in a community or slowing its spread once there—just such minor successes—would have saved many, many thousands of lives.

By early October the first fall outbreaks and the memory of those in the spring had already suggested that the virus attacked in a cycle; it took roughly six weeks from the appearance of the first cases for the epidemic to peak and then abate in civilian areas, and from three to four weeks in a military camp with its highly concentrated population. After the epidemic abated, cases still occurred intermittently, but not in the huge numbers that overwhelmed all services. So Red Cross and Public Health Service planners expected the attack would be staggered just as the arrival of the virus was staggered, peaking in different parts of the country at different times. During the peak of the epidemic, individual communities would not be able to cope; no matter how well organized they were they would be utterly overwhelmed. But if the Red Cross and Public Health Service could concentrate doctors, nurses, and supplies in one community when most needed, they might be able to withdraw the aid as the disease ebbed and shift it to the next area in need, and the next.

It transformed kitchens in public schools—which were closed—into soup kitchens that prepared meals for tens of thousands of people too ill to prepare their own.

The telephone company increased the isolation: with eighteen hundred telephone company employees out, the phone company allowed only emergency calls; operators listened to calls randomly and cut off phone service of those who made routine calls.

Very likely half a million—possibly more—Philadelphians fell sick.

On the single day of October 10, the epidemic alone killed 759 people in Philadelphia. Prior to the outbreak, deaths from all causes—all illnesses, all accidents, all suicides, and all murders—averaged 485 a week.

During the week of October 16 alone, 4,597 Philadelphians died from influenza or pneumonia, and influenza killed still more indirectly. That would be the worst week of the epidemic. But no one knew that at the time. Krusen had too often said the peak had passed. The press had too often spoken of triumph over disease.